Aaron Barany
Since OpenGL is deprecated on iOS, it is advantageous to be able to remove all OpenGL related code when building SDL for iOS. This patch adds the necessary #if checks to compile in this case.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
